Identification of Oral Prevotella Spp. From Periodontitis-Free Mothers

Objectives: Pigmented Prevotella species have a role in the healthy oral microbiota as well as in oral infections. The aims of this study were 1) to identify pigmented Prevotella spp. to the species level using modern diagnostic methods and 2) to compare their occurrence in saliva and plaque samples collected from mothers at post-partum.

Methods: Stimulated saliva and pooled subgingival plaque samples from 28 periodontitis-free mothers were collected 4-6 weeks after the delivery for anaerobic culture. Based on colony morphology and pigmentation, 10-15 different colonies per specimen were isolated from selective KVLB agar plates. Biochemical testing included alpha-galactosidase and beta-N-acetylglucosaminidase production, hydrolysis of esculin, and gas-liquid chromatography determination of carbohydrate fermentation (cellobiose, glucose, lactose, sucrose). Each Prevotella isolate with a distinct profile from each other and/or from ATCC type strains was further identified by partial sequencing (ca. 550 bp) of the 16S rRNA gene.

Results: Altogether 257 Prevotella isolates were selected to be identified by molecular methods. Among the 156 salivary isolates, P. melaninogenica, P. pallens, and P. denticola were the most frequently detected species, while P. denticola and P. nigrescens were common in plaque. In addition, P. aurantiaca, a newly described species within the P. intermedia group, was also found in these periodontitis-free mothers. When comparing the identification results obtained from biochemical testing and sequencing, all isolates presumptively identified as P. loescheii were re-identified as P. denticola, P. melaninogenica, and P. salivae by sequencing.


Conclusions: A variety of Prevotella species can be found in the oral cavity of periodontitis-free mothers. Bacterial findings in maternal saliva are of interest in the context of transmission of bacteria between mother and her child.